Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Feb 18th, 2015–Feb 19th, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Natural avalanches unlikely.

Regions

Purcells.

The snow is best up high, but this is also where lingering avalanche concerns exist. Please become a member of Avalanche Canada today at avalanche.ca/membership.

Confidence

Good

Weather Forecast

The ridge of high pressure flattens on Thursday allowing a couple weak disturbances to cross the province. We should see more cloud with possible light flurries each day. The freezing level is around 1500-1700 m on Thursday and should lower to around 800-1000 m by Saturday. Winds are light gusting moderate from the W-NW. The ridge rebuilds on Friday but we might not see full clearing until late Saturday. After this it looks like at least a few more days of dry and sunny weather.  

Avalanche Summary

Early this week there were several reports of natural and explosive triggered slabs and cornice falls to size 3. Almost all of these slides occurred on high alpine slopes with cornice related activity being specific to NE-E slopes below ridges. On Tuesday there were also reports of fresh wind slabs (10-20 cm thick) being reactive to skier traffic.

Snowpack Summary

Expect to find surface crusts on solar aspects and all aspects to at least 2000 m. At alpine elevations, thin new wind slabs or storm slabs may be found and cornices are large and weak. Underneath newly formed near-surface crusts, you may find moist snow. The late-Jan crust/surface hoar layer is 1-2 m deep in the west, and can be found within the upper metre of the snowpack further east. It is variably reactive and still the main concern in many areas. The mid-January surface hoar, deeper again, remains problematic in some areas. The mid-December and mid-November weak layers of crusts and facets can still be found near the bottom of the snowpack, particularly in shallower eastern parts of the Purcells.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.